1. Field of the Invention
The present invention relates to a disc drive equipped with a disc tray, and in particular relates to an improved disc tray for a disc drive that is used for playing back or recording and playing back an optical disc such as a CD-ROM or a CD-R or the like.
2. Description of the Prior Art
As shown in FIG. 1, a disc drive 1 for an optical disc, such as a CD-ROM drive or the like, is basically constructed from a main body 2 and a disc tray 5' which moves backwards and forwards (horizontally) with respect to the main body 2 for conveying an optical disc 3.
In this connection, FIGS. 13 and 14 are cross-sectional views showing a structure of a prior art disc drive in a simplified manner. As shown in these drawings, the main body 2 includes a circuit substrate assembly 12, a mechanism assembly 13 provided above the circuit substrate assembly 12, and a casing 10 which houses the circuit substrate assembly 12 and the machine assembly 13.
The casing 10 is constructed from thin metal plates and the like, with the front portion of the casing 10 being provided with a front panel 15 that includes an opening 15a, as shown in FIG. 1. The disc tray 5' is designed to be ejectable out of and insertable into the main body 2 via this opening 15a.
Further, as shown in FIGS. 13 and 14, the mechanism assembly 13 includes a chassis 40 and a mechanism unit 42 supported on the chassis 40. The rear portion of the mechanism unit 42 basically includes a base member 44 which is pivotally supported to the chassis 40 in order to enable the front portion of the mechanism unit 42 to be displaced between a raised position (upper position; see FIG. 13) and a lowered position (lower position; see FIG. 14) which is below the raised position. This base member 44 is provided with a spindle motor 45 for rotating an optical disc 3, a turntable 46 which is fixed to a rotation axle 45a of the spindle motor 45 for supporting the optical disc 3, an optical pick-up 47 (including an actuator) for playing back or recording and playing back the optical disc 3, and an optical pick-up moving mechanism (not shown in the drawing) for moving the optical pick-up 47 in the radial direction of the optical disc 3.
Arranged above the chassis 40, at a position which faces the turntable 46 when the base member 44 is displaced to the raised position, is a disc clamper 80 which is provided rotatably and movably in up and down. This disc clamper 80 is rotatably supported on a plate-shaped support member 81 having an aperture 81a formed in the center thereof.
The disc clamper 80 includes a flat-bottom, drum-shaped main body portion 80a which is inserted through the aperture 81a of the support member 81, and a flange portion 80b formed around the periphery of the upper portion of the main body portion 80a so as to be supported by the upper surface of the support member 81. Provided inside this main body portion 80 is an annular iron attraction member (not shown in the drawings) adapted to be attracted by a permanent magnet (not shown in the drawings) provided in the turntable 46.
As shown in FIG. 15, the disc tray 5' includes a shallow concave disc supporting portion 5a. The optical disc 3 is placed into the disc supporting portion 5a of the disc tray 5' with being positioned with respect to the disc tray 5', the optical disc 3 is conveyed from a disc loading/unloading position (disc eject position) to a disc loaded position (disc playback position).
Further, the disc tray 5' includes an opening 20, with the turntable 46 and the optical pick-up 47 being positioned below the opening 20 when the disc tray 5' is positioned at the disc loaded position.
In the disc drive described above, if the disc tray 5' on which the optical disc 3 is placed is moved from the disc loading/unloading position to the disc loaded position, then the base member 44 is moved from the lowered position (FIG. 14) to the raised position (FIG. 13). On the other hand, at the time of ejection, first the base member 44 is moved from the raised position (FIG. 13) to the lowered position (FIG. 14), and then the disc tray 5' is moved from the disc loaded position to the disc loading/unloading position.
As shown in FIG. 13, when the base member 44 is at the raised position, the turntable 46 is raised above the disc supporting portion 5a of the disc tray 5' through the opening 20 to hold up the disc 3 in a state that enables the disc 3 to be rotated, and in this state the disc clamper 80 is attracted to the magnet of the turntable 46, whereby the disc 3 is held therebetween. At this time, as shown in FIG. 13, the flange portion 80b of the disc clamper 80 is separated from the upper surface of the support member 81.
On the other hand, when the base member 44 is moved to the lowered position, as shown in FIG. 14, the turntable 46 is separated from the disc clamper 80 and the flange portion 80b of the disc clamper 80 is supported by the upper surface of the support member 81. In this state that the base member 44 has been moved to the lowered position, the lower end of the main body portion 80a of the disc clamper 80 partly protrudes into the concave portion which forms the disc supporting portion 5a of the disc tray 5'.
Consequently, in this prior art disc drive, in order to prevent the disc clamper 80 from obstructing the movement of the disc tray 5' when the disc tray 5' is moved from the disc loaded position to the disc loading/unloading position, a concave portion 21' for avoiding the disc clamper 80 is formed on a part of the disc tray 5' which passes a position where the lower end of the disc clamper 80 is being positioned when the disc tray 5' is moved, that is a part of the disc tray 5' which extends from the rear side of the opening 20 to the rear end of the disc tray 5'.
However, in a case where such a concave portion 21' is formed on the part of the disc tray 5', the part must be formed into a thin plate-like part made from a resin material, so that the strength of that part is relatively low in comparison with the opposite sides of that part (concaved portion 21'). In this regard, the opposite sides can be reinforced by forming reinforcement ribs on the back surfaces thereof to increase their strength, thereby preventing cambering (warpage) from being caused when hardening in cooling process. In contrast with this, it is not possible for the concave part 21' to provide such reinforcement ribs, that is it is simply formed from a thin plate-shaped resin material, there is a case that cambering is likely to be caused when hardening in cooling process. In the event that such a cambering is cased, the disc tray 5' is deformed, which results in a problem in that the deformed disc tray 5' can not be smoothly moved due to unfavorable contact with other parts.
Further, in order to avoid the disc clamper 80, there may be such approach that the length of the aperture of the disc tray is extended close to the rear end of the disc tray. However, in this approach, because there is a restriction on the length of the disc tray due to the standardization of the entire length of the disc drive, the width of the remaining rear part of the disc tray 5' becomes extremely narrow, and this makes it impossible to provide the disc tray with sufficient strength.